FindIce: Update documentation

- Module documentation synced with other similar find modules.
- Added examples section.
- Extended components into a separate section.
- Components listed with hlist RST directive
- Added and updated versions for variables when they got introduced.
- Fixed variable name from Ice_ICEBOXXX11_EXECUTABLE to
  Ice_ICEBOX++11_EXECUTABLE.
- Fixed typo in C++ component name: s/IceGrid/IceGrid++11